The present invention relates to power converter circuits for use in power supply, battery backup or uninterruptible power supply and other power conversion applications. More particularly, it relates to the implementation of an exemplary power module concept featuring high input power factor, simplicity of design, low-cost and good efficiency. The power module circuit having a single-stage and employing only a single-switch incorporates a hybrid of duty cycle and frequency control to achieve low total harmonic distortion (THD), low peak current stress on the transformer secondary circuit elements and low electromagnetic interference (EMI).
The conventional scheme used for AC-DC power conversion employs a diode rectifier-capacitor filter combination at the front end as shown in FIG. 1A. While this scheme is straightforward and economical, it severely deteriorates the quality of the AC supply by drawing peak currents near the peak of the input AC voltage as shown in FIG. 1B. This current is rich in harmonics (total harmonic distortion, THD, is very high) and results in poor power factor. There are several major disadvantages associated with having high harmonics injected back into the power grid such disadvantages include overheating of the distribution lines, distribution transformers and the neutral line interference with communication and control signals, over-voltages due to resonance conditions and most importantly an ineffective utilization of the voltage-ampere (V-A) rating of the utility.
With regulatory agencies more vigilant about power quality and the appropriate standards, e.g. with IEC-555-2 in place, consistent efforts have been made by engineers to develop new circuits for power factor correction (PFC) and/or THD reduction. In conjunction with the PFC circuits, new control schemes have also been proposed. Such is the popularity of some of these circuits and control schemes that manufacturers have come up with specialized integrated circuits (IC)s (e.g. MC34262, UC3854, etc.) dedicated to these circuits.
The following publications are relevant background information to the present invention although not all cited publications are prior art to the present application. Such may be referred to hereinafter by their ordinal numbers in brackets, e.g. the Kochar et al article might be referred to simply as [1].
[1] M. J. Kochar and R. L. Steigerwald, “An AC to DC converter with high quality input waveforms,” Proceedings of IEEE Power Electronics Specialists Conference, pp. 63–75, 1982.
[2] M. F. Schlecht, B. A. Miwa, “Active power factor correction for switching power supplies,” IEEE Transactions Power Electronics, Vol. 2, No. 4, pp. 273–281, 1987.
[3] H. Akagi, “Trends in active power line conditioners,” IEEE Transactions on Power Electronics, Vol. 9, pp. 263, May 1994.
[4] R. Redl, L. Balogh and N. Sokal, “A new family of single stage isolated power factor correctors with fast regulation of the output voltage,” IEEE Power Electronics Specialists Conference, pp. 1137–1144, 1994.
[5] R. Erickson, M. Madigan and S. Singer, “Design of a simple high-power-factor rectifier based on the flyback converter,” IEEE Applied Power Electronics Conference and Exposition, pp. 792–801, 1990.
[6] A. R. Prasad, P. D. Ziogas and S. Manias, “A new active power factor correction method for single phase buck boost AC-DC converter,” Proceedings of APEC, pp. 814–820, 1992.
[7] Eric X. Yang, Y. Jiang, G. Hua and F. C. Lee, “Isolated boost circuit for power factor correction,” Proceedings of APEC, pp. 196–203, 1993.
[8] M. Kheraluwala, R. Steigerwald and R. Gurumoorthy, “A fast response high power factor converter with a single power stage,” IEEE Power Electronics Specialists Conference, pp. 769–779, 1991.
[9] Matteo Daniele, Praveen K. Jain and Geza Joos, “A single-stage power-factor-corrected AC/DC converter,” IEEE Transactions on Power Electronics, Vol. 14, No. 6, pp. 1046–1055, November 1999.
[10] H. Wei, Issa Batarseh, G. Zhu and P. Kornetzky, “A single-switch AC-DC converter with power factor correction,” IEEE Trans. on Power Electronics, Vol. 15, No. 3, pp. 421–430, May 2000.
[11] H. E. Tecca, “Power Factor Correction using merged flyback-forward converters,” IEEE Transactions on Power Electronics, Vol. 15, No. 4, pp. 585–594, July 2000.
[12] M. M. Jovanovic, D. M. C. Tsang and F. C. Lee, “Reduction of voltage stress in integrated high quality rectifier regulators by variable frequency control,” Proceedings of Applied Power Electronics Conference (APEC), pp. 569–575, 1994.
[13] Serge Bontemps and Denis Grafham, “Low-loss resonant gate drive saves energy and limits EMI in 3.5 kW hard-switched PFC boost-converters,” PCIM 2002 (Europe), Nuremberg, Germany.
[14] Madhuwanti Joshi and Vivek Agarwal, “EMI mitigation in power electronic circuits operating at high power factor,” Proceedings of the IEEE International Conference on Industrial Technology 2000, Goa India, pp. 267–271.
[15] V. N. Shet, “Power Factor Correction in Power Converters,” Ph. D. Dissertation, Dept. of Electrical Engineering, IIT-Bombay, 2002.
[16] R. P. Stratford, “Rectifier harmonics in power systems,” IEEE Trans. Ind. Appl. Vol. IA-16, pp. 271–276, 1980.
[17] W. Shepherd, P. Zand, “Energy flow and power factor in nonsinusoidal circuits,” (London: Cambridge University Press), 1979.
[18] International Electrotechnical Commission Sub-Committee 77A, “Disturbances in supply system caused by household appliances and similar electrical equipment,” Draft Revision of IEC Publication 555.2, 1992.
[19] F. C. Schwarz, “A time-domain analysis of the power factor for a rectifier filter system with over and subcritical inductance,” IEEE Trans. Ind. Electron. Control Instrum., IECI-20(2), pp. 61–68, 1973.
[20] Vorpe'rian, R. Ridley, “A simple scheme for unity power-factor rectification for high frequency AC buses,” IEEE Trans. Power Electron 5, pp. 77–87, 1990.
[21] P. Jain, “A unity power factor resonant AC/DC converter for high frequency space power distribution system,” IEEE Power Electron. Spec. Conf., Rec. 1, 1994.
[22] A. R. Prasad, P. D. Ziogas, S. Manias, “A novel passive waveshaping method for single phase diode rectifiers,” IEEE Trans. Ind. Electron., IE-37, pp. 521–530, 1990.
[23] K. Yamashita, “Harmonics fighters pursue choke-coil, on converter power supplies”, Nikkei Electron., Asia, pp. 44–47, August 1994.
[24] Jih-Sheng Lai, D. Hurst, T. Key, “Switch mode power supply power factor improvement via harmonic elimination methods,” IEEE Appl. Power Electron. Conf., Rec., pp. 415–422, 1991.
[25] A. R. Prasad, P. D. Ziogas, S. Manias, “A Comparative evaluation of SMR converters with and without active input waveshaping,” IEEE Trans. Ind. Electron. IE-35(3), pp. 461–468, August, 1988.
[26] N. Mohan, T. M. Undeland, R. J. Ferraro, “Sinusoidal line current rectification with a 100 kHz BN-SIT step up converter,” IEEE Power Electron. Spec. Conf., Rec., pp. 92–98, 1984.
[27] B. Andreyeak, C. H. Yeam, J. A. O. Connor, “UC3852 controlled on-time zero current switched power factor correction preregulator,” Design Guide (Preliminary), Application note U-132, Unitrode Power Supply Design Seminar Manual, SEM 800, 1991.
[28] P. N. Enjeti, R. Martinez, “A high performance single phase AC to DC rectifier with input power factor correction,” IEEE Appl. Power Electron. Conf., Rec., pp. 196–203, 1993.
[29] M. S. Dawande, G. K. Dubey, “Bang bang current control with predecided switching frequency for switch mode rectifiers,” IEEE Power Electron Drives Syst. Conf., Rec., pp. 538–542, 1995.
[30] C. Zhou, R. B. Ridley, F. C. Lee, “Design and analysis of hysteretic boost power factor correction circuit,” IEEE Power Electron. Spec. Conf., Rec., pp. 800–807, 1990.
[31] J. J. Spangler, A. K. Behera, “A comparison between hysteretic and fixed frequency boost converters used for power factor correction,” IEEE Appl. Power Electron. Conf., Rec., pp. 281–286, 1993.
[32] W. Tang, F. C. Lee, R. B. Ridley, I. Cohen, “Charge control: Modelling, analysis and design,” IEEE Power Electron. Spec. Conf., Rec., pp. 503–511, 1992.
[33] W. Tang, Y. M. Jiang, G. C. Hua, F. C. Lee, I. Cohen, “Power factor correction with flyback converter employing charge control,” IEEE Appl. Power Electron. Conf., Rec., pp. 293–298, 1993.
[34] H. Endo, T. Yamashita, T. Sugiura, “A high power factor buck converter,” IEEE Power Electron. Spec. Conf., Rec., pp. 1071–1076, 1992.
[35] D. Maksimovic, R. Erickson, “Universal-input, high-power-factor, boost doubler rectifiers,” IEEE Appl. Power Electron, Conf., Rec., pp. 459–465, 1995.
[36] Bakari M. M. Mwinyiwiwa, P. M. Birks, Boon-Teck Ooi, “Delta-modulated buck-type PWM converter,” IEEE Trans. Ind. Appl. 28, pp. 552–557, 1992.
[37] Boon-Teck Ooi, Bakari M. M. Mwinyiwiwa, X. Wang, G. Joos, “Operating limits of the current-regulated delta-modulated current-source PWM rectifier,” IEEE Trans. Ind. Appl., 38, pp. 268–274, 1991.
[38] P. C. Todd UC 3854, “Controlled power factor correction circuit design,” Unitrode-Product Applications Handbook, Lexington, Mass., 1993–94.
[39] Micro Linear Data Book, 1993
[40] R. Oruganti and M. Palaniapan, “Inductor voltage controlled variable power factor buck—type AC-DC converter,” Proceedings of Power Electronics Specialists Conference (PESC), pp. 230–237, 1996.
[41] R. Oruganti and Ramesh Srinivasan, “Single phase power factor correction—A review,” Sadhana, vol. 22, part 6, pp. 753–780, 1997.
[42] F. C. Schwarz, “A time-domain analysis of the power factor for a rectifier filter system with over and sub-critical inductance,” IEEE Tran. on Ind. Electron. Control Instrumentation, IECI-20(2), pp. 61–68, 1973.
[43] A. R. Prasad, P. D. Ziogas, S. Manias, “A novel passive waveshaping method for single phase diode rectifiers,” IEEE Tran. Ind. Electron., IE-37, pp. 521–530, 1990.
[44] I. Takahashi, R. Y. Igarashi, “A switching power supply of 99% power factor by the dither rectifier,” IEEE International Telecommunication Energy Conference Record, pp. 714–719, 1991.
[45] M. Madigan, R. Ericson, E. Ismail, “Integrated high quality rectifier regulators,” IEEE Power Electronic. Spec. Conference, pp. 1043–1051, 1992.
[46] M. S. Elmore, W. A. Peterson, S. D. Sherwood, “A power factor enhancement circuit,” IEEE Applied Power Electron. Conf. Record, pp. 407–414, 1991.
[47] Vivek Agarwal, V. P. Sundarsingh, Serge Bontemps and Denis Grafham, “A Smart Power Converter Module for Buck Applications Operating at High Input Power Factor,” Proceedings of the 28th Annual Conference on Industrial Electronics, Control and Instrumentation (IECON), Sevilla, Spain, pp. 858–863, 2002.
[48] Vivek Agarwal, V. P. Sundarsingh, Serge Bontemps, Alain Calmels and Denis Grafham, “Novel single-switch isolated 42V/1 kW battery charger module uses converter operating at near-unity Power Factor,” Proceedings of PCIM-2003, Nuremberg, Germany, May 20–22, 2003.
[49] Yufu Wang, “Boost converter with lower inter-phase rectifier parallel compensating three-phase power factor correction,” Chinese Patent Application No. 01140014.5, Nov. 20, 2001.
[50] L. Umanand and S. R. Bhat, “Design of magnetic components for switched mode power converters”, First Edition, Willey Eastern Limited, 1992.
[51] Y. F. Zhang, L. Yang and C. Q. Lee, “EMI reduction of power supplies by Bi-Frequency modulation,” Proceedings of the Ninth Annual Applied Power Electronics Conference and Exposition, pp. 601–607, 1994
The advantages of a high power factor and low harmonic distortion are well known. A major advantage is an optimum utilization of power coming out of the utility [1, 16–18]. The past two decades have witnessed a tremendous research effort related to power factor correction in switching power supplies [1–49]. This could be attributed to the growing awareness about power quality and the seriousness with which the concerned agencies all over the world have started enforcing power quality standards.
For purposes of highlighting the novelty of the present invention, prior art schemes will be reviewed first.